Ashless additive for fuels



March 7, 1961 H. R. ERTELT ETAL ASHLESS ADDITIVE FOR FUELS Filed Jan. 24, 1958 ACCELERATED STORAGE STABILITY TEST 0.003 WT. TOTAL ADDITIVE I I I I I I I I I AMINE A 0 POLYMER A I00 I0 I00 90 80 70 60 50 40 30 20 I0 0 ADDITIVE COMPOSITION Henry R. Enel'r Edward F. Perlowski, Jr. Inventors Thomas S. Turwiler By Wu Attorney 2,974,025 ASHLESS ADDITIVE FOR FUELS Henry R. Ertelt, Fanwood, N.J., Edward F. Perlowski, Jr., Lenox, Mass., and Thomas S. Tutwiler, Plainfield, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Jan. 24, 1958, Ser. No. 711,067

11 Claims. (Cl. 44-62) The present invention relates to stabilized petroleum oils, in particular to liquid fuels that are subject to formationtof sediment and discoloration, in storage or upon being heated. More particularly, the present invention relates to the stabilization of liquid fuels and fuel oils against sediment formation and color degradation, with additive compositions which will not form ash or residue upon combustion. In one embodiment, the present invention relates to an improved aviation turbo fuel that is highly thermally stable and less subject to deteriorative changes and deposit formation in storage or in use than presently available aviation turbo fuels. The present invention is a continuation-in-patt of Serial No. 552,740, filed December 13, 1955, and now abandoned.

Intermediate boiling petroleum distillate fractions, or middle distillates, as they are known in the art, find wide use as fuels, e.g. as fuel oils in the burner systems employed in domestic and industrial heating systems and as diesel fuels. It is common practice to incorporate distillates from the cracking of petroleum in these fuels, and the presence of cracked distillates has aggravated sediment formation. It has been found that the use of by volume or more of cracked distillates in these fuels may markedly increase formation of sludge or sediment during the time the fuel is in storage, and this sediment later may cause plugging or fouling of the filters, lines, and nozzles in the burner systems in which they are employed. It has further been found that the formation of sediment is accelerated when the fuels are heated in heat exchangers and that in some critical applications in which the temperature exceeds 300 F. some separation of objectionable, very finely divided, insoluble particles may occur even in the absence of cracked distillates.

Several other problems have also been encountered with these intermediate distillate fuels. Some materials that have been added to these fuels to stabilize them against sediment formation have given rise to emulsion problems, occasioned when fuels containing these additives come in contact with water in storage tanks or in pipe lines. It has been found that certain additives under these conditions cause the water and oil to form emulsions that are extremely stable and difiicult to resolve. Also, it is desirable to have these fuel oils stable against color degradation, even if no sedimentation occurs.

In the operation of aircraft using turbo-je and turbo-prop engines, a serious problem is the forma- ZfiMflZS Patented Mar. 7., 1961 tion of fuel deposits from light distillate fuels not con- 'taining cracked distillates. Furthermore, a problem arises in the plugging of fuel filters at low temperatures. Depositsin the fuel nozzles of a jet engine are very undesirable in that they disrupt the desired fuel spray patterns in the combustors, thereby causing uneven combustion which results in Warping of the liners and in decreasing the amount of power that can be generated. Aviation turbo fuels must be thermally stable because in service they are heated to'temperatures as high as 500 F. by being circulated through a heat exchanger, which cools the lubricating oil from the engine. If even minute proportions of unstable constituents are present, the heat exchangers, screens and nozzles in the fuel system become fouled with the insoluble material formed from those constituents, thus causing malfunction of the engine.

Typical aviation turbo fuels, so made as to minimize deposit formation and other diificulties that have been encountered in the operation of jet aircraft, conform with United States military specifications as shown in Table I.

TABLE I SPECIFICATION MIL-F-5624O Aviation Turbo-Jet Fuel, Grade .TP-4 JP-S JP-fi Gravity, API. 36-48 37-50 Freezing Poiut, F 76 55 65 Aromatics, Vol. Percent 25 25 25 Olefius, Vol. Percent 5 5 5 Existeut Gum, mg./100 ml- 7 7 5 Potential Gum, rug/100 ml Max 14 14 1O Sulfur, Total Wt. Percent Max 0. 4 0. 4 0. 4 Mercaptau Sulfur, Wt. Percent Max. 0.005 0. 005 0.001 Heating Value, Net b.t.u./1b -i in 18, 400 18,300 18, 400 Reid Vapor Pressure, p.s.i 2-3 Water Tolerance, ml

Corrosion, Copper Strip Test. Pass Pass Pass Viscosity, es. at 30 F .Ma 16. Viscosity, cs. at -40 F Max 15 Distillation:

Initial Boiling Point, F Min 250 10% Min. Evaporation at, F H 400 20% Min. Evaporation at, F. 50% Min. Evaporation at; I Min. Evaporation at, F- Final Boiling Point, F

Residue, Vol. Percent Max 1. 5 l. 5 1. 5

Loss, Vol. Percent Max 11.5 1. 5 1.5 Thermal Stability:

Hg AP at 40')/500/6 Max 10 Max. Preheater Tube Deposit Lt. Tan

1 Or pass Doctor Test.

Max. pressure drop in CFR Fuel Coker after 5 hours at (iii/hr. full flow rate, 400 F. fuel temperature, '500 I filter temperature. Equivalent to a Merit Rating of 510.

Turbo jet fuels for use in commercial aircraft are normally obtained from selected refined distillates boiling in these acids.

factory for stabilizing these turbo jet fuels. Only severe acid treating has produced a satisfactory thermally stable turbo jet fuel. This process is not only expensive, but entails substantial product losses in acid sludge.

Accordingly, it is a primary object of the present invention to improve the stability of petroleum fuelsand fuel oils against the formation of sediment. The particular fuel oils embraced by the present invention include the fuel oils falling with A.S.T.M. specification, D39648T, for fuel oils (grades 1 and 2). Also useful in accordance with the present invention are diesel'fuel oils No. 1D, No. 2-D, and No. 4-D of A.S.T.M. specification D975 5 1T. The fuels include the turbo jet fuels falling within Specification MIL-F-5624C.

It has in the past been found that certain dispersing and surface-active agents, including certain nitrogen-containing polymeric compositions, have a stabilizing effect upon heating oils and diesel fuels. The polymethacrylate polymers in particular have been used for this purpose. However, in concentrations high enough to afford a reasonably good storage stability, the sludge dispersant properties of some of these polymers have caused water emulsions and tank sediment pick-up problems.

It has also been known in the past to'stabilize hydrocarbon oils against sludge formation by the incorporation of certain amine compounds. The efiectiveness of these has not been wholly satisfactory.

It has now been found that oil-soluble polymeric nitrogen-containing dispersants, when used with tertiary alkyl primary amines of 8 to 27 carbon atoms give synergistic combinations that are unusually effective in improving fuel stability, leave no ash on combustion, reduce the emulsion problem and are substantially superior to either component added alone in equivalent amounts.

The polymer constituent that is incorporated in accordance with the present invention is preferably an oil-soluble copolymer, the components of which comprise a compound from the group consisting of the acrylic and alphasubstituted acrylic esters of aliphatic alcohols having an average of at least 8 carbon atoms in the molecule, and an ethylenically unsaturated compound containing an amino group. In a preferred embodiment of this invention, the proportion of these nitrogenous monomers will preferably be such that the basic amino nitrogen content of the copolymer will be in the range of about 0.2 to about 3.5 wt. percent. Other amine-free ethylenically unsaturated compounds which will'copolymerize with the above monomers may also be included, e.g. styrene or alkyl styrenes.

'Thus the alkyl acrylates in the copolymer used in the present invention are those of acrylic and alpha-substituted acrylic acids wherein the alpha substituent, ifpresent, is preferably a lower alkyl radical, with aliphatic alcohols having an average of at least 8 carbon atoms in the molecule, and preferably 12 to 18 carbon atoms. Examples are the tridecyl, lauryl, cetyl and octadecyl esters of acrylic and methacrylic acids,' as well asthe L'orol esters of I Lorol. refers to the primary alcohol mixture, ofq to Q carbon atoms, obtained by the hydrogenation of coconut oil. It is described in U.S. 2,560,588

and varies in average molecular distribution from C to C Typical distributions are as follows:

- Weight percent It is to be understood, therefore, that the term Lorol here means a mixture of normal aliphatic alcohols having from 10 to 18 carbon atoms and particularly about" 50% to about of C alcohol.

The polymerizable ethylenically unsaturated compounds containing a basic amino group, forming one of the components of the copolymer, include preferably the basic tertiary amino-alkyl acrylates, such as the dialkyl aminoalkyl acrylates and alpha hydrocarbon-substituted acrylates, beta dimethylaminoethyl acrylate and methacrylate, and their homologs and analogs. The amino nitrogen may be a member of a heterocycle wherein the polymerizable ethylenic unsaturation is extranuclearly bonded to the heterocycle, such as the vinyl pyridines and p-dirnethyl amino ethyl styrene. Other unsaturated compounds which copolymerize with monomers above described may also be used in the preparation of the dispersant copolymers. Examples of such monomers include styrene and alkyl styrenes, butadiene, and olefins having terminal unsaturation, such as isobutylene.

Particularly useful as dispersants have been found to be the 80/20 copolymer of Lorol methacrylate/diethyh amino ethyl methacrylate andthe copolymer of Lorol methacrylate and aminoisobutyl methacrylate. Polymeric dispersants of this type are fully described in British Pat ent 734,632, published August 3, 1955, and in U.S. Patent. 2,737,452, published March 6, 1956.

The second component of the ashless additive is a primary amine in which .the carbon atom attached to the amino group is a tertiary carbon atom.

Where all of the groups attached to the tertiary carbon atom are alkyl groups, it is preferred that one of the alkyl groups have from 5 to 21 carbon'atoms, and that the other two alkyl groups have from 1 to 3 carbon atoms. Particularly satisfactory are tertiary alkyl primary amines having two methyl groups attached to a tertiary carbon atom, for example, 2,4,4rtrimethyl-2-aminopentane, and t-C H NH These may be conveniently prepared by amination of olefin polymers, such as diisobutylene, triisobutylene, tetraisobutylene and/or tri, tetra and polypropylene. The aminated tetrapropylene, t-C H NH is especially effective.

Tertiary alkyl primaryamines suitable for use in accordance with the present invention can be prepared from tertiary olefins, for example polymers ofpropylene or isobutene and from copolymers of propylene and isobutene, as well as from copolymers of isobuteneandbutenes or'pentenes.

Such polymers and copolymers' are well known synthetic olefins in the petroleum industry. For instance, propylene polymers ranging in molecular size from the dimer of six carbon atoms to the tetramer of twelve carbon atoms are made, in mixtures of suitable volatility for use in motor gasoline, by polymerizing propylene in the presence of catalysts which are made by impregnating silica gel suitably with phosphoric acid. Also, in the manufacture of iso-octane for use in aviation gasoline, isobutene has been converted to diisobutene by polymerization with sulfuric acid ascatalyst and then to isooctane by hydrogenation. Of course, the manner of preparation of the polymers or olefins is not at the point of novelty of the present invention, nor is the manner of preparation of primary amines from olefins, which, as is well known, can be aminated with ammonia. Suffice it to say that an olefin like the dimer of isobutene can be converted, for example, to 2-amino-2,4,4-trimethylpentane and 2-amino-2,3,4 trimethyl-pent-ane, each of which is a primary amine having an ar'nino radical attached to a tertiary carbon atom in an alkyl group of group is derived from a polymeric'olefin which naturally tures result and produce double bonds elsewhere than at the end of the longest chain. In a polymerization not only structural variations but also irregularities of molecular weights occur; and at any given set of conditions of reaction the final equilibrium produces a mixture of olefins.

Consequently, the tertiary alkyl primary amines, suitable for use in accordance with the present invention, when they are made from tri-isobutene, which is a polymer of isobutene having tertiary carbon atoms in a molecule containing 12 carbon atoms, may contain some tertiary alkyl amines of 13, 14 and/or 15 carbon atoms as well as the predominant one of 12 carbon atoms. Such a mixture is conveniently designated as t-C H NH a tertiary alkyl primary amine having predominantly 12 carbon atoms per molecule and having minor proportions of homologous molecules with 13, 14 and/or 15 carbon atoms. Similarly, when making a suitable tertiary alkyl primary amine of 18 carbon atoms from hexa-propylene, a polymer of propylene, one obtains a mixture conveniently designated as t-C H NH which in context is understood to be a tertiary alkyl primary amine having predominantly 18 carbon atoms per molecule and having minor proportions of homologous molecules with 19, 20, 21, 22, 23 and/ or 24 carbon atoms.

Specific examples of tertiary alkyl primary amines suitable for use in accordance with the present invention are the following:

6-amino-2,2,4,4,6,8,8-heptamethyl-nonane 2-amino-2,3 ,4,6,6,8,8-heptamethyl-nonane 4-amino-2,3 ,4,6,6,8,S-heptamethyl-nonane 4-amino-2,4,6-trimethyl-nonane 3-amino-3 ,5 ,S-trimethyl-nonane 3-amino-3,4,6-trimethyl-nonane 3-amino-3,6-dimethy1-decane 3-amino-3,5-dimethyl-decane 4-amino-4-methyl-undecane 4-amin0-2,4,6,8, IO-pentamethyl-tridecane 3-amino-3 ,5,7,9,12-pentamethyl-tridecane S-amino-S,l3-dimethyl-hexadecane Specially preferred for use in accordance with the present invention is the material designated as which was made from tetrapropylene and which by actual analysis upon degradation to its constituent olefin by reaction with nitrous acid was shown to consist essentially of tertiary dodecyl primary amine.

In further accordance with the present invention there is a critical ratio of polymer to amine composition wherein synergism reaches a sharp peak. On either side of this the synergistic properties decrease rapidly. This ratio may differ for any two different combinations.

Concentrations in the oil of 0.0005 to 0.0225 wt. percent active ingredient of the various types of surfaceactive polymers described above are suitable for use in conjunction with the amines of the type defined by the present invention. Particularly preferred concentrations of such polymers are from 0.0015 to 0.01 wt.'percent active ingredient. The ratio of amine to polymer in the additives of the invention will generally be in the range of 2:1 to 18: 1, preferably 3:1 to 8:1, where the polymer is considered on an active ingredient basis. The concentration of the amine-polymer mixture in fuel will be in the range of about 0.001 to about 0.045% by weight, preferably 0.0025 to 0.02% by weight.

The various additives mentioned above, both of the amine and polymer types, may be added directly to the fuel as such or in the form of an oil-soluble concentrate. A suitable oil solvent 'for the preparation of a concentrate is preferably an oil of good quality, for example, a solvent-extracted paraflinic or Mid-Continent neutral oil falling within a viscosity range at 210 F. of 30 to 120 Saybolt Universal seconds or a fuel oil of many of the grades hereinbefore designated.

Of the various polymeric additives to be used in combination with the amine additives, an 80/20 Lorol methacrylate B-diethylaminoethyl methacrylate copolymer is preferred and outstanding. It is made by copolymerizing 80 parts of Lorol methacrylate with 20 parts of 3- diethylaminoethyl methacrylate.

The nature of this invention will be more fully understood from the following examples: I

A. To 44.5 gms. /z mol) of warm 2-amino-2-methyll-propanol was added 0.2 gm. of metallic sodium. The

resulting reaction product was combined with 150 gm. (1.5 mols) of freshly distilled and inhibited methyl methacrylate monomer in a 3-necked flask equipped with stirrer, thermometer and trap to collect methanol-methyl methacrylate azeotrope. Mixture was heated and stirred at 65 to 75 C. for 2 hours until ml. of liquid had been collected in trap. Reaction product was washed with 20% potassium carbonate (5% in potassium hydroxide) a total of five times. Product was nitrogen blown on steam bath to remove traces of methyl methacrylate and filtered.' Yield=66% B. A solution of 98 gm. (0.5 mol) of Lorol B alcohol and 2.6 gm. of para toluene sulfonic acid in 125 gm. (1.25 mols) of freshly distilled and inhibited methyl methacrylate monomer was charged into a 3-necked flask equipped with stirrer, thermometer and trap to collect methanol-methyl methacrylate azeotrope. Stirring and heating this solution for 2 /2 hours at approximately 70 to 80 C. resulted in ml. of liquid being collected in the trap. Product in flask was-washed three times with sodium hydroxide solution (2%) and five times with distilled water. An ether solution of the washed product was further washed with carbonate solution and dried. Yield of Lorol B methacrylate after ether removal was 96.8 gm. (77%).

II. POLYMERIZATION A mixture of 61.5 gm. of Lorol B methacrylate, 11.5 gm. of Z-amino-Z-mcthyl-l-propyl methacrylate, 73 gm. of toluene and 0.15 gm. (0.2% of u,u-azo-di-isobutyronitrile was charged into a 3-neckedv flask equipped with stirrer, thermometer and reflux condenser. Mixture was heated and stirred for 21 hours atv 60 to 70 C. Reaction product was nitrogen blown on steam bath to remove toluene. Yield of highly viscous amber polymer was 71.5 gm. 197%). A 50 weight percent of this polymer in a heating oil was designated as Polymer B.

Polymer A was prepared in an analogous manner from Lorol 5 methacrylate and B-diethyl aminoethyl methacrylate.

Example 2 Gravity, A.P.I. Color, Robinson 7 Pensky-Martens flash, F 1 85 Sulfur, wt. percent 0.34- Neutralization No 0.02 Aniline point, F 109.6

A.S.T.M. distillation range:

I.B.P. F 328 10% 392 50% 479 90% 581 F.B.P., F 635 Conradson carbon residue, wt. percent 0.007

mitted referred to the unheated base fuel.

TABLE II.NITROGEN-CONTAINING POLYMER+ AMINE COMBINATION Weight Percent Additive Component in Blend Accelerated Storage Stability (16 Hours 210 F.) Polymer Amine Amine A Mg. Sedl- Percent Col- Polymer A tClQHfiNHZ meant/600 g. orhold (unoil heated-100) None None 18. 4 58 0. 004 None 16. 5 40 0. 00188 None 23. 6 49 None 0.005 4. 6 83 None 0.0025 5. 8 85 0.002 0.0025 2. 7 73 Polymer B t-C H NHZ None None 17. 7 58 0. 003 None 6. 37 None 0. 003 6. 2 83 0.0015 0.0015 4. 1 67 Polymer C lZ-CuHflNHQ None None 20.2 67 0. 004 None 6. 42 None 0. 004 5. 4 84 0.0013 0.0027 3. 3 77 Polymer A is an 80/20 copolyrner of Lorol 5 methacrylate S-diethylaminoethyl methacrylate. It is added to the kerosine or oil as an approximately 50 weight percent blend in a petroleum white oil, which is a well known article of commerce.

Polymer B is a 50 weight percent solution of a copolymer of Lorol B methacrylate and Z-amino isobutyl methacrylate in No. 2 fuel oil.

Polymer C is made from the same ingredients as Polymer A save that it is a 90/ 10 copolyrner, and is a 50 weight percent solution of the copolymer in No. 2 fuel oil.

Lorol B is a mixture of C to C alcohols, of which @6% is C alcohol, 24% 'is C alcohol, 10% is C al- :ohol, 17% is C alcohol and 3% is C alcohol.

Lorol 5 is a similar mixture having.6l% C 23% 314;. C1, C13,v and CuyfilCOhOL Amine A is a mixture of tertiary alkyl primary amines derived from tetrapropylene;

Referring to the above table, it will be noted that although the addition in each case of either the dispersantpolymer or the amine had a stabilizing effect upon sediment formation in. the heated oil, the addition of the combination had a substantially greater effect upon the stability of the fuel than could have beenpredicted from the sum of the two effects taken separately. In the case of Polymer A and the-tertiary alkyl primary amine, the ratio of amine to polymer giving the most pronounced stabilizing eifect is about 3:1. This is shown graphically in the figure. Synergistic effects became particularly pronounced in the range of amine-to-polymer ratios between 1:1 and 9:1, in respect of storage stability where the polymer is considered as a 50% solution. On a polymer active ingredient basis the synergistic effect is particularly pronounced in the amine to polymer ratio range of 2:1 to 18:1, more particularly at 3:1 to 8:1 and reaches an optimum at about 6:1. The ratios above 1:1 are particularly beneficial for color hold.

The data in Table II demonstrate that nitrogen-containing polymers of the methacrylate type, when blended into oils to which have been added certain primary amines wherein the amine group is linked to a tertiary carbon atom, form synergistic combinations having excellent stabilizing elfects upon the oil.

It has likewise been found that in the ease of the nitro-' gen-containing methacrylate polymers, in order to obtain a synergistic effect, the amine or amine derivative must be a tertiary alkyl primary amine. This is shown in Table III below:

The alkyl secondary amine, (C H NH, is a mixture in which the alkyl groups vary from C H t0 C18H37- Example 3 An important property of the ashless additive combination of the present invention is that it combines good stabilizing action with low emulsification tendencies. This advantage is particularly important at higher additive concentrations. As the data below show, a blend of three parts of Amine A and one part of Polymer A has substantially less emulsification tendencies than Polymer A alone. The data in Table II have already defined these materials and shown the superior stabilizing properties of this combination. The Herschel machine has long been a standard piece of equipment in petroleum' laboratories. The test is used for turbine oils, -'as in A.S.T.M. 134401-561".

TABLE IV.--HERSCHEL EMULSIFICATION TESTS OF LIQUID FUEL BLENDS 77 F.

Additive- None Polymer A 3 Parts Amine A, 1 Part Polymer A Base Oil A 1 Wt. Percent in Blend 0. 007 0.015 0. 02 007 0. 015 0.02

After Minutes:

O11 Separated, cc 40 40 39 32 40 40 40 Emulsion, cc 0 40 41 48 0 2 2 Water Separated, cc 40 0 0 0 40 38 38 Base 011 B 2 Wt. Percent in Blend 0. 005 0. 02 0.005 0. 02

After 15 Minutes:

Oll Separated, cc 40 40 41 40 Emulsion, cc 0 5 60 0 4 Water Separated, cc- 40 0 39 36 Base Oil 0 Wt. Percent in Blend-. 0.008 008 After 15 Minutes:

Oil Separated, co 40 40 Emulsion, cc 0 4 1 0 Water Separated, cc 40 39 40 1 AA No. 2 heating oil, A.S.T.M. D936-48T B-Diesel fuel, non caustic washed, grade 1D; A.S.T.M. D-975-51T.

* C-.TP5 type (kerosine) turbo jet fuel. 4 Creamy.

Table IV shows that the additive combination of the invention gives fuel blends showing low tendency to form emulsion. As is well known, this is a critical pergnimance requirement for turbo jet fuels such as Base These laboratory results have been borne out in pipeline service field tests.

Example 4 The results of the accelerated storage stability test were confirmed by the accelerated filter plugging test. This test is described in detail in New Fast Test Method for Distillate Storage Stability by W. A. Konrad, N. L. Shipley and T. S. Tutwiler, which is found on page 145 of Petroleum Processing, September 1956. Briefly, the accelerated filter plugging (AFP) test consists of heating a sample of test oil at a controlled rate for 16 hours to a final temperature of 230 F. to accelerate the formation of sediment. The sample is then cooled and drawn through a felt filter pad at a constant rate of one gallon per hour. As sediment accumulates on the filter under constant oil flow conditions, the pressure drop across the filter increases. After filtration of 12 liters, the required throughput for the test, a record is made of the final pressure drop across the filter, the weight of sediment collected and the appearance of the filter. These criteria are interpreted individually on a demerit basis in which 0 is excellent and 10 is bad, and are arithmetically averaged to obtain the overall AFP demcrit for the test oil.

TABLE V.ACCELERATED FILTER PLUGGING TEST [Base: 50% virgin, 50% catalytic heating oil] Wt. Percent of Additive Overall Components in Blend AFP Demerit None .7 0.007 Polymer A 2.3 0.007 Amine A 3.3 0.007 Polymer A/Amine A (1:3) 1.3

tive composition of the present invention on the color hold of heating oil is shown below, in comparison with larger concentrations of a commercial additive and of Polymer A, which is one of the ingredients of the additive of the present invention, in a commercial heating oil consisting of 70% cracked gas oil, 15% virgin waterwhite distillate, and 15% virgin heavy naphtha.

TABLE VI.EFFECT OF ADDITIVES ON COLOR HOLD OF HEATING OIL IN STORAGE The commercial additive was one containing sodium sulfonate. Polymer A was the same as in Table II. The mixture of Amine A and Polymer A in 3:1 ratio was. the same as in Table IV. Tag Robinson Color is a standard test in the petroleum industry and is measured on the colorimeter described in TAG Manual, 23rd edition, page 56, published by C. I. Tagliabue Mfg. Co.- The higher the Robinson number, the lighter is the color of the sample of oil.

' In addition, the ashless additive composition of the present invention was tested in turbo jet fuels of the types shown in Table I. The necessary levels of thermal stability of turbo jet fuels are measured by the CFR fuel coker test. High stability jet fuels of the LIP-5 and JP-6 type have a specification of a CFR fuel coker merit rating of 500 minimum. The CFR fuel coker is essentially a scaled down version of a full scale turboengine fuel-system which stimulates the heat exchanger. Fuel degradation is measured by the pressure drop across a heated 20 micron metal filter and by a visual rating of the varnish-like deposits laid down on the-heat exchanger tube. The pressure drop data are translated into an arbitrary merit rating.

Example 6 The additive composition of the present invention is heating oils and therefore have inherently less tendency to form sediment; but, as explained previously, a small improvement in this tendency in the former type of fuel has great practical significance for utility. The advantage of using the additive composition of the present inven-. tion in aviation turbo fuel is shown by an accelerated oxidation test in which a sample of the fuel is oxidized for 16 hours under 100 p.s.i. oxygen pressure at 212 F. with results as follows:

TABLE VII Additive in JP-5 Kerosine as Defined in Table I Mgs. Sedi- Test N 0. went per Liter Additive Wt.

Percent None 43 Polymer A as in Table IV. 0.002 43 Polymer A as in Table IV 0. 008 42 Amine A and Polymer A (3:1)

as in Table IV 0.008 35 Example 7 Besides the thermal stability problem involved with JP fuels, a further problem associated with the severe conditions under which JP fuels are employed is that of forming varnish-like surface deposits which tend particularly to coat heat exchanger tube surfaces. This is a highly undesirable phenomenon in jet planes and engines. In a further embodiment of the present invention there is incorporated in the JP fuel, along with the synergistic combinations of Polymer A and Amine A, a small amount of a class of amines, Well known in the art as metal deactivators for use in copper-sweetened gasoline. This is the class of N,N'-disalicylidine-di-amino alkanes, wherein the alkane can be ethane, propane, butane or pentane, and the amino groups are on carbon atoms separated by nomore than one carbon atom. A particularly desirable member of this class is N,N'-disalicylidine-1,2-propane-diamine. This material is preferably added dissolved in a vehicle, such as xylene. Furthermore, the composition is added in the critical range of 0.003 to 0.009%. As the data in Table VIII show, above and below this amount do not achieve. the desired degree of effectiveness, when used with 0.01% of a mixture of Amine A and Polymer A in 3:1 weight ratio.

TABLE VIII-CPR FUEL COKER TESTS [Base iuel: Kerosine J P45] Merit Tube Rating Deposits 2 Target-as listed in Military Specifications 500 Light tan,

(min) max. color. Additives: 1-None 100 Dark brown. 2-0.01 Wt. Percent Additive F 650 Do. 3-0.01 Wt. Percent (I T,N disal c 1,2 propane diamine, 80% in xylene). 50 4-0.01 Wt. Percent Additive F+0.0l Wt. Percent (N ,N disalicylidine 1,2 propane diamine 80% in xylene) 450 Brown. 5-0.0l Wt. Percent Additive F+0.001 Wt. Percent (N,N disalicylidine 1,2 propane diarnine 80% in xylene) 220 6-0.01 Wt. Percent Additive F+0.005 Wt. Percent (N,.- l disalieylidine 1,2 propane diamine 80% in xylene) 700 Trace stain.

1 Test Conditions:

400 F. i'uel temperature. 500 F. filter temperature. 6 lbs/hr. fuel fiow rate.

This is a standard test of the Coordinating Research Council of the Am. Pet. Inst. and Soc. of Automotive Engineers-CRO Manual No. 3, March 1957.

1 Preheater tube deposits rated visually after 300 minutes of operation.

3 3 parts by weight of Amine A and 1 part of Polymer A.

,Solution of 80% by weight cf-N.N" disalieylidine 1,2 propane dia- E inc in xylene.

12 TABLE IX.-EFFECT OF ADDITIVE F ALONE ON THERMAL STABILITY OFR Fuel Coker Tests Merit Preheater Test Rating Tube Condi- Deposits 1 tions Target -t 500 g2 Virgin Mid-Continent Dis 7 as in Table I 3 300, 410 a l, 1 300l400 Virgin Mid-Continent Dis as in Table I+0.01 Wt. percent Additive F 4 3 900, 900 3 1, 0 300 400 Hydrofined Kerosino .TP5. 290 3 400/500 Hydrofined Kerosine JP-5 +0 percent Additive F 4 Q00 3 400/500 Virgin Kerosine JP-5 as in Table I 5 4 400l500 Virgin Kerosine JP-5.as in Table +0.01 Wt. percent Additive F 900 4 400l500 Virgin Kerosine JP5 as in Table I. v V 5 4 400l500 Virgin Kerosine J P-5 as in Table I 1 +0.01 Wt. percent Additive F L... 3 875, 700 5 4, 4 ION/500 1 Prebeater Deposit Scale:

O-Clean. 1Haze or dulling; no visible discoloration. 2-Barely visible discoloration. 3-Light tan to peacock stain. 4-Heavier than Code 3. 2 Preheater temperature/filter temperature. All runs at Git/hr. fuel flow rate.

3 Repeat; runs. Additive F as in Table VIII. 5 Tube deposits measured after full test time of 300 minutes of operation.

Example 8 When JP fuels are exposed to nuclear radiation at normal engine operating conditions, they degrade to form sediment and deposits which clog the engine fuel system resulting in critical reductions in fuel flow. The addition of Additive F as in Table VIII (3 parts by weight of Amine A plus 1 part by weight of Polymer A) to petroleum distillate JP fuel results in a fuel blend which has adequate stability even when exposed to high radiation dosages and high temperatures. Data showing the stabilizing effect of Additive F are presented in the following table. The experiments were conducted in the CFR fuel coker. Gamma radiation was applied to the fuel just before, and during passage through the preheater tube of the fuel coker.

TABLE X.-EFFECT OF ADDITIVE F ON JP FUEL [Radiation stability at soc/400 F. I in the CFR fuel coker] Fuel Radiation Filter AP, Time Dose, Reds in. Hg. (Min) Kerosine ZIP-5 0 2. 5 300 Kerosine .TP-fi 0. 7 X10 6 25 100 Kerosine+Additive 0. 7X10 0 300 JP-4 as in Table 1.... 0 4.5 300 LIP-4 as in Table I- 0. 7X10 25 42 JP-4+Additivo F 9 0. 7X10 0 30 l Prehcater/filter temperature. 2 0.01% by Weight.

At a preheater/filter temperature of 400/ 500 F., the following results were obtained:

Kerosine .lP-5 0 25 50 Kerosine+0. 01% Additive F 0. 7X10 6 0 300 The stabilizing effect of Additive F is indicated by the very low pressure drop developed across the test filter of the fuel coker.

Example 9 TABLE X[.EFFECT OF ADDITIVE PLUS METAL DEACTIVATOR IN COMBINATION ON RADIA- TION STABILITY AT 400/ 500 F.

Total Filter AP, Time Fuel Radiation in. Hg. (IVIilL) Dose, Rads SIP- Kerosine+Additive F 2. 1X10 25 260 JP-5 Kerosine+Additive F 6. 5x10 25 273 JP-5 Kerosine+Additive F 9 +DMD a 4. 3X10 0.6 300 1 Preheater/filter temperature.

2 0.01% by weight of Additive F.

0.005% by weight of Metal Deactivator, N,N-disalicylidine-1,2 diamine propane.

Improved stability is indicated by the very low pressure drop developed across the test filter of the CFR fuel coker.

Example 10 TURBO JET ENGINE TESTS Test 1: 100 hour bench test-This test was run on IP-4 as in Table I blended with 0.01 wt. percent Additive F as in Example 7 and having the following characteristics in the CPR coker test:

FUEL COKER TESTS AT 300 131/400 F.

Base fuel 270 merit rating, clean tube. Base-+0.01% Additive F 670 merit rating, clean tube.

Engine operation during 100 hour test was satisfactory. The engine appeared very clean on teardown.

Test 2: 100 hour bench test.--Test was run on flight grade JP-4 plus 0.02 wt. percent Additive F. Operation satisfactory. Engine clean. Additive F was the same as in Example 6.

Example 11 A copolymer is prepared by reacting together, according to the method given in Example 2, 55 parts Lorol 7 methacrylate, 25 parts octyl styrene and parts fi-dimethylaminoethyl methacrylate. A 50 weigh-t percent solution of this copolymer in kerosine is blended with an equal weight of 1-amino-1,1,3,3-tetramethyl butane to give a superior stabilizer for heating oils and turbo-jet fuels. Lorol 7 alcohol is a mixture of C to C alcohols having 55.5% C 23% C 10% each of C and C alcohols and 3% C alcohol.

Example 12 The method of Example 2 is used to prepare a copolymer from 50 parts decyl methacrylate, 30 parts octadecyl styrene and 20 parts 4-vinyl pyridine. One pant of a 50 weight percent solution of this copolymer in No. 2 heating oil mixed with five parts of 2-amino-2,4,4,6,6, 8,8,10,14 nona methyl-octadecane is an example of the improved fuel stabilizers of this invention.

Example 13 34 weight of one part of an oil-soluble dispersant copolymer of (a) an ester selected from the group consisting of the acrylic esters of C to C unsubstituted aliphatic alcohols and the alpha substituted acrylic esters of said alcohols in which the alpha substituent is a lower alkyl group and (b) a tertiary amine alkyl acrylate, said copolymer con taining from about 0.2 to about 3.5 wt. percent of basic amino nitrogen, and fiom about 2 to about 18 parts by weight of a tertiary alkyl primary amine containing from 8 to 27 carbon atoms per molecule.

2. A fuel as defined by claim 1 wherein said tertiary alkyl primary amine has attached to the tertiary carbon atom one alkyl group of from 5 to 21 carbon atoms and the other alkyl groups have from 1 to 3 carbon atoms.

3. A fuel as defined by claim 1 wherein said fuel has a boiling point range of between about 300 and about 750 F 4. A fuel as defined by claim 1 wherein said fuel contains additionally from 0.003 to 0.009% by weight of an N,N-disalicylidine-diamino alkane.

5. A fuel as defined by claim 1 wherein the ratio of said amine to said copolymer is from 3:1 to 8:1.

6. A fuel as defined by claim 1 wherein said fuel contains from 0.0025 to about 0.02% by weight of the copolymeramine mixture.

7. A petroleum distillate fuel having a 20% by volume minimum distillation temperature of more than 290 F. containing from about 0.001 to about 0.045% by weight of a mixture of (a) the copolymer of the C to C primary alcohol ester of methacrylic acid and B-diethylamino methacrylate, said copolymer containing from about 0.2 to about 3.5 wt. per cent of basic amino nitrogen, and (b) a mixed tertiary alkyl primary amine having the formula C H NH the ratio of said amine to said copolymer being in the range of from 2:1 to 18:1.

8. The fuel composition of claim 7 wherein said ratio of said amine to said copolymer is about 6: 1.

9. The fuel composition of claim 7 containing from 0.003 to 0.009% by weight of an N,N'-disa1icylidine-diamino alkane metal deactivator.

10. The fuel composition of claim 9 wherein said metal deactivator is N,N-disalicylidine-1,2-propane-diamine.

11. A petroleum distillate fuel having a 20% by volume minimum distillation temperature of more than 290 F. containing from about 0.001 to about 0.045 by weight of a mixture of (a) the copolymer of the C to C primary alcohol ester of methacrylic acid and Z-amino isobutyl methacrylate, said copolymer containing from about 0.2 to about 3.5 wt. percent of basic amino nitrogen, and (b) a mixed tertiary alkyl primary amine having the formula C H NH the ratio of said amine to said copolymer being in the range of from 2:1 to 18:1.

References Cited in the file of this patent UNITED STATES PATENTS 2,524,864 Wies et al. Oct. 10, 1950 2,639,227 Glendenning et a1 May 19, 1953 2,641,539 Thompson et a1. June 9, 1953 2,684,292 Caron et a1. July 20, 1954 2,737,452 Catlin et a1. Mar. 6, 1956 2,805,925 Biswell Sept. 10, 1957 2,945,749 Andress July 19, 1960 OTHER REFERENCES Tertiary-Alkyl Primary Amines, Rohm & Haas Co., Special Products Dept, Bulletin SP-33, September 1954, pages 3 and 16. 

